1. ECE 477 Group 3 The Gauntlet George Hadley Kelli Hacker Sean Ma Jacob Champion

2. Critical Safety and Reliability Issues Battery undervoltage – possible explosion causing injury to the user Battery undervoltage – possible explosion causing injury to the user GPS malfunction during “emergency mode” – does not lead user back to a safe point, possibility of becoming more lost GPS malfunction during “emergency mode” – does not lead user back to a safe point, possibility of becoming more lost Sensor malfunction – loss of functionality Sensor malfunction – loss of functionality

3. Components Most Likely to Fail Complexity Complexity PIC24 microcontroller PIC24 microcontroller VS1011E MP3 decoder VS1011E MP3 decoder Heat Heat LTC3440 Buck-boost dc/dc converter LTC3440 Buck-boost dc/dc converter MCP73811 Linear charge manager MCP73811 Linear charge manager

4. FMECA Analysis - Power Power Subsystem Failure No. Failure ModePossible CausesFailure EffectsMethod of Detection CriticalityRemarks A1Power rail = 0 VShort, disconnect in power supply circuit Nothing turns on or operates ObservationLow A2Power rail > 3.3 V Buck-boost failure, short to battery Damage to components throughout circuit, loss of functionalilty ObservationLow A3Battery undervoltage Analog comparator fails, excessive noise on buck-boost output, charger fails Possible battery explosion ObservationHigh A4Battery overvoltage Charger fails and short circuits Possible battery explosion ObservationHigh

5. FMECA Analysis - Microcontroller Microcontroller Subsystem Failure No. Failure ModePossible CausesFailure EffectsMethod of Detection CriticalityRemarks B1Microcontroller receives < 3.3 V Bypass capacitor shorts Microcontroller will not operate, no functionality ObservationLow B2External oscillator fails Failure of individual components No audio output, errors more likely in LCD communication ObservationLow B3Microcontroller stuck in loop Loss of communication with sensors Loss of functionality ObservationLow

6. FMECA Analysis - Audio Audio Subsystem Failure No. Failure ModePossible CausesFailure EffectsMethod of Detection CriticalityRemarks C1MP3 decoder receives < 3.3 V Bypass capacitor shorts Audio does not operate ObservationLow C2MP3 decoder chip stops working Decoder receives ESD, output capacitors short Audio does not operate ObservationLow

7. Mitigating Safety and Reliability Concerns Battery undervoltage – analog comparator used, can change resistor values for greater safety margin Battery undervoltage – analog comparator used, can change resistor values for greater safety margin Add code to jump out of polling loop and mitigate loss of sensor information Add code to jump out of polling loop and mitigate loss of sensor information

8. Questions?